Abstract: Bacteria self-propel in fluids using a complex apparatus called flagella. In each flagellum, a specialised motor rotates a helical filament located outside the cell; the rotation of each motor is transmitted to a short flexible segment called the hook which in turn transmits it to a flagellar filament, enabling viscous propulsion and swimming of the whole cell. In this talk I will highlight recent work from my group on the locomotion of bacteria where flows and hydrodynamic interactions lead to self-organisation and instabilities. I will first summarise an investigation on the collective dynamics of confined bacteria that are biased to swim in a preferred direction. I will next show how the the swimming of cells with multiple flagella is enabled by an elastohydrodynamic instability. I will finally explain how wall-cell hydrodynamic interaction can lead to a transition to a wall-bound state for the swimming bacteria.

Bio: Eric Lauga is Professor of Applied Mathematics at the University of Cambridge and a Fellow of Trinity College, Cambridge. He graduated from Ecole Polytechnique (France) in 1998 and the Corps des Mines Program from Ecole des Mines de Paris in 2001. After receiving an M.S. in Fluid Mechanics from University of Paris Pierre et Marie Curie (France) in 2001, he earned his Ph.D. in Applied Mathematics from Harvard University in 2005 where he worked in theoretical modeling of flow phenomena at the micron scale. Prior to joining Cambridge, he was on the faculty at MIT (Mathematics) and at the University of California, San Diego (Mechanical and Aerospace Engineering). He is a recipient of the NSF CAREER award (2008) and of three awards from the American Physical Society: the Andreas Acrivos Dissertation Award in Fluid Dynamics (2006), the François Frenkiel Award for Fluid Mechanics (2015) and the Early Career Award for Soft Matter Research (2018). He is a Fellow of the American Physical Society. His research interests include the development of theoretical approaches to model viscous flows, in particular in a biological context, the dynamics of complex fluids and interdisciplinary problems in soft matter physics. He joined PRFluids as an Associate Editor in 2016.